This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:    3GPP third generation partnership project    BS base station    DL downlink (eNB towards UE, or RN towards UE)    eNB E-UTRAN Node B (evolved Node B)    DeNB donor eNB    HeNB home eNB    EPC evolved packet core    E-UTRAN evolved UTRAN (LTE)    FDM frequency division multiplex    HII high interference indicator    IMTA international mobile telecommunications association    ICIC intercell interference coordination    ITU-R international telecommunication union-radiocommunication sector    LOS line of sight    LTE long term evolution of UTRAN (E-UTRAN)    LTE-A LTE advanced    MAC medium access control (layer 2, L2)    MBSFN multi-media broadcast over a single frequency network    MM/MME mobility management/mobility management entity    NodeB base station    OFDMA orthogonal frequency division multiple access    OI overload indicator    O&M operations and maintenance    PDCP packet data convergence protocol    PHY physical (layer 1, L1)    PRB physical resource block    PSS primary synchronization signals    Rel release    RLC radio link control    RN relay node    RNTP relative narrowband transmit (Tx) power    RRC radio resource control    RRM radio resource management    RSRP reference signal received power    RSRQ reference signal received quality    RSSI received signal strength indicator    SGW serving gateway    SC-FDMA single carrier, frequency division multiple access    SINR signal to interference plus noise ratio    SSS secondary synchronization signals    TDM time division multiplex    TTI transmission time interval    UE user equipment, such as a mobile station, mobile node or mobile terminal    UL uplink (UE towards eNB or RN)    UPE user plane entity    UTRAN universal terrestrial radio access network
One modern communication system is known as evolved UTRAN (EUTRAN, also referred to as UTRAN-LTE or as E-UTRA). In this system the DL access technique is OFDMA, and the UL access technique is SC-FDMA.
One specification of interest is 3GPP TS 36.300, V8.11.0 (2009-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage (Release 8), incorporated by reference herein in its entirety. This system may be referred to for convenience as LTE Rel-8. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.211, 36.311, 36.312, etc.) may be seen as describing the Release 8 LTE system. More recently, Release 9 versions of at least some of these specifications have been published including 3GPP TS 36.300, V9.3.0 (2010-03).
FIG. 1 reproduces FIG. 4.1 of 3GPP TS 36.300 V8.11.0, and shows the overall architecture of the E-UTRAN system (Rel-8). The E-UTRAN system includes eNBs, providing the E-UTRAN user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UEs. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME by means of a S1 MME interface and to a S-GW by means of a S1 interface (MME/S-GW). The S1 interface supports a many-to-many relationship between MMEs/S-GWs/UPEs and eNBs.
The eNB hosts the following functions:
functions for RRM: RRC, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both UL and DL (scheduling);
IP header compression and encryption of the user data stream; selection of a MME at UE attachment;
routing of User Plane data towards the EPC (MME/S-GW);
scheduling and transmission of paging messages (originated from the MME);
scheduling and transmission of broadcast information (originated from the MME or O&M); and
a measurement and measurement reporting configuration for mobility and scheduling.
Of particular interest herein are the further releases of 3GPP LTE (e.g., LTE Rel-10 and beyond) targeted towards future IMTA systems, referred to herein for convenience simply as LTE-Advanced (LTE-A). Reference in this regard may be made to 3GPP TR 36.913, V9.0.0 (2009-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE-Advanced) (Release 9). Reference can also be made to 3GPP TR 36.912 V9.2.0 (2010-03) Technical Report 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Feasibility study for Further Advancements for E-UTRA (LTE-Advanced) (Release 9).
A goal of LTE-A is to provide significantly enhanced services by means of higher data rates and lower latency with reduced cost. LTE-A is directed toward extending and optimizing the 3GPP LTE Rel-8 radio access technologies to provide higher data rates at lower cost. LTE-A will be a more optimized radio system fulfilling the ITU-R requirements for IMT-Advanced while keeping the backward compatibility with LTE Rel-8. As is specified in 3GPP TR 36.913, LTE-A should operate in spectrum allocations of different sizes, including wider spectrum allocations than those of LTE Rel-8 (e.g., up to 100 MHz) to achieve the peak data rate of 100 Mbit/s for high mobility and 1 Gbit/s for low mobility. It has been agreed that carrier aggregation is to be considered for LTE-A in order to support bandwidths larger than 20 MHz. Carrier aggregation, where two or more component carriers (CCs) are aggregated, is considered for LTE-A in order to support transmission bandwidths larger than 20 MHz. The carrier aggregation could be contiguous or non-contiguous. This technique, as a bandwidth extension, can provide significant gains in terms of peak data rate and cell throughput as compared to non-aggregated operation as in LTE Rel-8.
Relay nodes can be used to extend cell coverage, in particular to provision high data rates in high shadowing environments (e.g., indoor coverage) and to enhance cell capacity with low cost for LTE-A systems.
Reference can be made to Section 9 “Relaying functionality” of 3GPP TR 36.814 V9.0.0 (2010-03) Technical Report 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Further advancements for E-UTRA physical layer aspects (Release 9).
Further by example, reference can be made to 3GPP TR 36.806 V9.0.0 (2010-03) Technical Report 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Relay architectures for E-UTRA (LTE-Advanced) (Release 9). This technical report discusses various architectures that have been proposed to implement the relay functionality. An architecture A is based on a termination of both the U-plane and the C-plane of the S1 interface at the RN. This architecture is then differentiated in a basic variant, Alt 1 and two other variants, Alt 2 and 3. In an architecture B the DeNB acts as the termination for S1 connections towards the EPC, and the RN can be simply seen as a cell managed by the DeNB from EPC and neighbor eNBs point of view. The DeNB acts as a S1-AP gateway, similar to a HeNB gateway.